UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(D) OF

THE SECURITIES EXCHANGE ACT OF 1934

~~September~~November 1118, 2025

Date of Report

(Date of earliest event reported)

Arrowhead Pharmaceuticals, Inc.

(Exact name of registrant as specified in its charter)

Delaware

001-38042

46-0408024

(State or other jurisdiction

of incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)

177 E. Colorado Blvd, Suite 700, Pasadena, CA 91105

(Address of principal executive offices, including Zip Code)

(626) 304-3400

(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:


☐			Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
☐			Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
☐			Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
☐			Pre-commencement communications pursuant to Rule 13e-4 (c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, par value $0.001 per share

ARWR

The Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01 Other Events

~~Arrowhead~~On ~~Pharmaceuticals, Inc. (the “Company”) was notified that on September~~November 1118, 2025, ~~Ionis~~Arrowhead Pharmaceuticals, Inc. ~~(“Ionis”)~~issued ~~filed~~ a ~~Complaint~~press ~~for~~release ~~Patent~~announcing ~~Infringement~~that ~~against~~ the ~~Company~~U.S. inFood ~~the~~and ~~United~~Drug ~~States~~Administration ~~District~~has ~~Court~~approved ~~for~~REDEMPLO® ~~the Central District of California alleging patent infringement of United States Patent No. 9,593,333~~ (~~“the ’333 patent”~~plozasiran)~~. As~~ ~~the~~as ~~Company~~an ~~previously~~adjunct ~~reported,~~to ondiet ~~September~~to ~~10,~~reduce ~~2025,~~triglycerides ~~the Company filed a Complaint for Declaratory Judgment~~ in ~~the~~adults ~~United~~with ~~States~~familial ~~District~~chylomicronemia ~~Court~~syndrome ~~for the District of Delaware against Ionis to declare that the ’333 patent is invalid and not infringed by the Company’s planned commercialization of investigational plozasiran~~(FCS). A ~~copy~~Arrowhead ofsubsequently ~~Ionis’s~~held ~~complaint~~a isconference ~~attached~~call ~~hereto~~discussing ~~as Exhibit 99.1 (~~the ~~“Complaint”)~~approval.

~~Forward-Looking~~A ~~Statements~~copy of this press release is attached as Exhibit 99.1 to this Current Report and incorporated herein by reference. A copy of the slides presented at the conference call is attached as Exhibit 99.2 to this Current Report and incorporated herein by reference.

This Current Report on Form 8-K contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Any statements contained in this report except for historical information may be deemed to be forward-looking statements. Without limiting the generality of the foregoing, words such as “may,” “will,” “expect,” “believe,” “anticipate,” “hope,” “intend,” “plan,” “project,” “could,” “estimate,” “continue,” “target,” “forecast” or “continue” or the negative of these words or other variations thereof or comparable terminology are intended to identify such forward-looking statements. These forward-looking statements include, but are not limited to, statements about our planned commercialization of investigational plozasiran and beliefs and expectations regarding the Company’s claims and lawsuits against Ionis and the validity and enforceability of the ‘333 Patent. These statements are based upon our current expectations and speak only as of the date hereof. Our actual results or outcomes may differ materially and adversely from those expressed in any forward-looking statements as a result of numerous factors and uncertainties, including the risks and uncertainties described in our most recent Annual Report on Form 10-K, subsequent Quarterly Reports on Form 10-Q and other documents filed with the Securities and Exchange Commission from time to time. We assume no obligation to update or revise forward-looking statements to reflect new events or circumstances.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.						Description
99.1						~~Complaint~~Press Release, dated November 18, 2025.
99.2						REDEMPLO Approval Conference Call November 18, 2025
104						Cover Page Interactive Data File (the cover page tags are embedded within the Inline XBRL document).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Date: ~~September 12~~November 18, 2025


ARROWHEAD PHARMACEUTICALS, INC.

By:						/s/ Daniel Apel
						Daniel Apel
						Chief Financial Officer

Filing Compare · ARROWHEAD PHARMACEUTICALS, INC.